America’s federal lands are increasingly threatened by thieves who make off with everything from mushrooms to cedar trees and sell the natural resources for profit. From 1991 to 1997, poachers stole 15,000 barrel cacti from federal lands in California, including the Mojave National Preserve, and sold them to makers of miznaga, a Mexican candy. Earlier this year, 10 people were convicted of hunting bears in Virginia’s Shenandoah National Park and selling the gall bladders and paws, which are prized overseas. In 1999, a crew of workers stole hundreds of thousands of dollars worth of bear grass, which is used in floral arrangements, from the Willamette National Forest in Oregon. Poachers often get away undetected because federal law-enforcement officers have such large expanses of land to patrol.